Mostafaei H.,NRC Institute for Research in Construction
Fire Safety Journal | Year: 2013
A new performance-based assessment approach for structures in fire, referred to as hybrid fire testing (HFT) method, is presented in this article. The HFT was developed based on a sub-structuring method, by dividing the whole structure into two substructures, one being tested in a furnace and one being simulated by a computer. This represents a form of hardware-in-the-loop simulation. Using HFT, the performance of the whole building can be evaluated at a very reasonable cost, significantly less than the cost of the direct whole building test. More reliable results than the prescriptive method can also be achieved with comparable and even more comprehensive results than that of a direct full-scale test. A 6-storey reinforced concrete building was designed, as a prototype for application of the hybrid fire testing approach. Two fire scenario examples were considered; a 6-storey building with a fire compartment on the first floor, in the center of the building and a 6-storey building with a fire compartment on the third floor. The two substructures for these two HFT scenarios were; one the column in the fire compartment and two the rest of the building. This paper includes the description of the hybrid testing methodology, details of the 6-storey building prototype and the methodology verification. Using the HFT approach, various scenarios could be explored to couple modeling and testing globally. This may also provide the possibility of running one test in a testing facility, e.g. NRC's, and running the analysis remotely at a different location. This would make furnace facilities more accessible to the research communities around the globe.© 2013 Elsevier Ltd. All rights reserved.
Saber H.H.,NRC Institute for Research in Construction
Building and Environment | Year: 2012
Reflective insulations are being used in home attics, flat roofs, sloped roofs and wall systems of building envelopes. The present model, hygIRC-C, was used to investigate the contribution of the reflective insulations to the thermal resistance of specimens. The predictions of the present model were compared with test data of different sample stacks with different types of reflective insulations. In a previous study, the present model was benchmarked using test data obtained from a Guarded Hot Box (GHB) in accordance with the ASTM C-1363 test method. In this study, the test data was obtained from a different test method based on the heat flow meter in accordance of ASTM C-518 in the case of horizontal sample stacks with reflective insulations. Results showed that the predicted heat fluxes on the same area and same location of Heat Flux Transducers (HFTs) on the top and bottom surfaces of the sample stacks are in good agreement with the measured heat fluxes (within ±1%). The derived R-values using these heat fluxes are also in good agreements. Due to the combined effect of heat transfer by convection and radiation in the airspace (facing the reflective surface), these predicted and measured heat fluxes are greater than the area-weighted average heat flux of whole sample stack, which is needed to determine the effective R-value of the sample. As such, the derived R-value from the test data resulted in underestimation of the effective R-value of the sample stack. After gaining confidence in the present model, it was used to conduct parametric study in order to quantify the contribution of reflective insulations to the effective R-value for a sample stack with different inclination angles, different directions of heat flow (upward and downward) and for a wide range of foil emissivity. Furthermore, the present model was used to compare the predicted R-values with the listed R-values in the 2009 ASHRAE Handbook  for enclosed air cavity (20mm thick) of different effective emittance, inclinations and directions of heat flow. © 2011.
Zuraimi M.S.,NRC Institute for Research in Construction
Indoor Air | Year: 2010
Ventilation duct cleaning (DC) is widely advocated to provide good indoor air quality (IAQ), health benefits, cost savings, and enhance ventilation system performance. The aim of the present review is to evaluate the scientific evidence as shown in the literature. There is evidence that under normal operating conditions, ventilation ducts can be contaminated with dusts and serve as reservoirs for microbials to proliferate. While controlled experiments noted that contaminants resuspension can elevate exposure levels indoors, no field studies have correlated poor IAQ with duct contamination. Despite high efficiencies of contaminant removal within the ducts during cleaning, reductions for different indoor air pollutants vary widely, where, post-cleaning air pollutants concentrations can be higher than pre-cleaning levels. Further, there are health concerns in the use of biocides, sealants and encapsulants. There is inadequate evidence to show that DC can improve airflow in ducts and reduce energy consumption. Although epidemiological studies indicate suggestive evidence that improperly maintained ducts are associated with higher risks of symptoms among building occupants, this review finds insufficient evidence that DC can alleviate occupant's symptoms. In summary, the need for duct cleanliness has to be properly balanced by the probable generation of indoor pollution resulting from DC and subsequent potential health risks. © 2010 National Research Council Canada.
Liu Z.,NRC Institute for Research in Construction |
Kleiner Y.,NRC Institute for Research in Construction
Measurement: Journal of the International Measurement Confederation | Year: 2013
This paper reviews the state-of-the-art of inspection techniques and technologies towards condition assessment of water distribution and transmission mains. Pipe condition assessment is the determination of its current condition, including structural health, impact on water quality, and hydraulic capacity. The collection and analysis of relevant data and information is the first and a paramount step to detect and monitor critical indicators to prevent or mitigate catastrophic failures. The technologies include conventional non-destructive inspection and advanced sensor techniques for condition monitoring. This paper focuses on the inspection techniques and technologies for structural deterioration of water pipes. Technologies like smart pipe, augmented reality, and intelligent robots are also briefly discussed and summarized. © 2012 Elsevier Ltd. All rights reserved.
Veitch J.A.,NRC Institute for Research in Construction
Healthcare Papers | Year: 2011
People spend much of their waking time in their workplaces (approximately 33% on a weekly basis), which raises the possibility that the conditions they experience at work influence their health and well-being. The workplace design literature has given scant attention to mental health outcomes, instead focusing on healthy populations. Conversely, the mental health literature gives scant attention to the potential contribution of workplace design in preventing mental health problems; nor does it provide much insight into facilitating return to work. Taken together, however, the literature does suggest both lines of research and possible interventions. Existing knowledge proposes that workplace design can influence mental health via the effects of light exposure on circadian regulation, social behaviour and affect; the effects of aesthetic judgement on at-work mood and physical well-being and at-home sleep quality; access to nature and recovery from stressful experiences; and privacy regulation and stimulus control. This paper includes a short review of the literature in this area, proposals for new research directions and consideration of the implications of this information on the design choices made by business owners, designers and facility managers. Providing suitable working conditions for all employees avoids stigmatizing employees who have mental health problems, while facilitating prevention and return to work among those who do.
Sato T.,NRC Institute for Research in Construction |
Beaudoin J.J.,NRC Institute for Research in Construction
Advances in Cement Research | Year: 2011
The efficacy of the addition of nano-CaCO3 in accelerating the hydration of ordinary Portland cement (OPC) delayed by the presence of high volumes of supplementary cementitious materials including fly ash and slag was investigated. The conduction calorimetry indicated that the early hydration of OPC was significantly accelerated by the addition of the nano-CaCO3 and the higher the amount of CaCO3 addition, the greater was the accelerating effect. The thermogravimetric analysis results showed that the amounts of added CaCO3 became slightly lower as the hydration took place; however, any new reaction products were not detected by the X-ray diffractometry analysis. The engineering properties, including microhardness and modulus of elasticity, in the early stage of the hydration were remarkably improved by the addition of nano-CaCO3. It was suggested that the seeding effect of the nano-CaCO3 particles and the nucleation of C-S-H caused the enhanced strength development.
Newsham G.R.,NRC Institute for Research in Construction |
Bowker B.G.,NRC Institute for Research in Construction
Energy Policy | Year: 2010
Peak demand for electricity in North America is expected to grow, challenging electrical utilities to supply this demand in a cost-effective, reliable manner. Therefore, there is growing interest in strategies to reduce peak demand by eliminating electricity use, or shifting it to non-peak times. This strategy is commonly called "demand response". In households, common strategies are time-varying pricing, which charge more for energy use on peak, or direct load control, which allows utilities to curtail certain loads during high demand periods. We reviewed recent North American studies of these strategies. The data suggest that the most effective strategy is a critical peak price (CPP) program with enabling technology to automatically curtail loads on event days. There is little evidence that this causes substantial hardship for occupants, particularly if they have input into which loads are controlled and how, and have an override option. In such cases, a peak load reduction of at least 30% is a reasonable expectation. It might be possible to attain such load reductions without enabling technology by focusing on household types more likely to respond, and providing them with excellent support. A simple time-of-use (TOU) program can only expect to realise on-peak reductions of 5%. © 2010 .
Bradley J.S.,NRC Institute for Research in Construction
Applied Acoustics | Year: 2011
ISO 3382-1 describes a number of objective room acoustics parameters that are generally accepted as useful for rating some specific aspects of concert hall sound fields. They include measures of decay times, energy ratios, measures of sound strength and several quantities related to the spatial aspects of sound fields. In most cases there are details of the measures, or their application, that raise questions. In general, there has not been a lot of practical research to explore how best to develop and use these objective measures to evaluate conditions in concert halls. For some well established measures such as Early Decay Time (EDT), we are not really sure how best to calculate their values. For other measures such as energy ratios, modifications are often proposed but without the support of subjective evaluations of the proposed changes. In other cases, such as measures of spatial impression, two approaches have been suggested, but their relative merits are not well understood. It is easy to propose ever more complex measures, but it is much more difficult to demonstrate their general utility. On the other hand, some commonly described characteristics do not have accepted related objective measures. Many more important and more general problems relate to the need, for design criteria in terms of each quantity, and for an improved understanding of just noticeable differences for each measure. This paper discusses each measure illustrating particular problems with measurements in various halls. © 2011 Elsevier Ltd. All rights reserved.
Maurenbrecher P.,NRC Institute for Research in Construction
Materials and Structures/Materiaux et Constructions | Year: 2012
This paper gives a summary of functional and performance requirements for repointing mortars for historic masonry (design, execution and maintenance). Successful performance of repair and conservation of mortar in historic masonry requires more care with design and execution than with modern masonry. © 2012 RILEM.
Saassouh B.,NRC Institute for Research in Construction |
Lounis Z.,NRC Institute for Research in Construction
Cement and Concrete Composites | Year: 2012
Concrete structures are subjected to chloride-induced corrosion that can lead to shortened service life. Reliable predictions of life cycle performance of concrete structures are critical to the optimization of their life cycle design and maintenance to minimize their life cycle costs. This paper presents two simplified semi-analytical probabilistic models based on the first-and second-order reliability methods to model the uncertainty of the key parameters including surface chloride concentration, chloride threshold, cover depth and diffusion coefficient, which govern the chloride ingress into concrete and corrosion of reinforcing steel. A case study of a reinforced concrete highway bridge deck is used to illustrate the capability and efficiency of these simplified probabilistic models in modeling the uncertainty and predicting the time-dependent probability of corrosion. The models enable to quantify the impact of the different governing parameters on probability of corrosion and service life, which can be used to develop cost-effective management strategies. © 2012 Elsevier Ltd. All rights reserved.